This site is very legit. They have a community forum over there where quite a few people have posted screenshots of the checks they got in the mail.

Playing the Game
After registration, you can begin winning! Pick 4 two digit numbers and 1 one digit bonus number and click the WIN!!! button. The game automatically checks your picks against all 9 simultaneous ways to win and immediately notifies if you won. Win cash or points and it's always FREE TO PLAY.

Points can be redeemed for gift cards or other NetWinner's Partner merchandise. Play the game as often as you want! And refer all your friends and win an additional 10% of everything they win!

NetWinner - You Play, We Pay!